Module 3
System Components
Case Form Factors
Form
Factor
ATX
Characteristics
The most common form factor for full-sized computers.
ATX boards measure 12" x 9.6“ and the CPU sits at the back top below the power supply. The power supply can use a
soft switch or soft power (the operating system can turn the computer off).
Mini-ATX
Slightly smaller variation of the full ATX (11.2” x 8.2”)
Micro-ATX
Smaller variation of the full ATX (9.6" x 9.6“)
Mini-ITX
Smallest variation of the ATX standard (6.7" x 6.7“)
NLX
NLX is an older form factor used for slimline desktop-style computers
BTX
The BTX form factor was designed to give developers better options for
managing system performance and balancing thermal management.
Mounting holes for both are located in the same place, making them interchangeable in most cases.
Mounting holes for both are located in the same place, making them interchangeable in most cases.
The mini-ATX standard also includes standards for a power supply that provides less than 100 Watts.
Uses a riser card for expansion slots in the middle of the system board. Supports AGP video cards.
The processor is at the front and turned on an angle to increase air flow across the processor.
Power Supply Facts
• Power supplies must be matched to the motherboard and case form
factor. ATX motherboard, purchase an ATX power supply.
• The power supply converts AC current to DC current and supplies provide
+ 3.3 volts, +/- 5 volts, and +/- 12 volts (DC power).
• Power supplies are rated in watts. The more devices you have in your
computer, the more wattage you will require. Calculate the system's
wattage requirements with the following method:
– Find the wattage requirements of each individual circuit by multiplying
volts by amps (W = V x A).
– Add the circuit wattage requirements together to find the total system
wattage requirement.
Power Supply Facts
• An ATX power supply provides soft power. This is a condition where the
motherboard always has power, even when the computer is turned off.
This feature enables the operating system to power off the system and
enables other features such as power on for network or other events.
• The power supply includes connectors for powering various computer
components. When choosing a power supply make sure it includes the
necessary connectors for your motherboard. Specifically, some
motherboards and processors require an extra 4-pin and/or 8-pin
connector in addition to the main 20- or 24-pin power connector.
• Power supply connectors are standardized following the ATX
specifications. However, some computer manufacturers, such as Dell,
produced power supplies with proprietary connectors.
Motherboard
Component
Function / Characteristics
Processor
interface
The motherboard socket must match the socket type and design used by the
processor. Some motherboards support multiple processors and will have a
socket for each processor.
Memory
modules
Memory modules must be compatible with the type supported by the
motherboard, total memory capacity, and the processor and chipset support.
Expansion
slots
Expansion slots allow you to add features to your computer by inserting
expansion cards into the available slots
Onboard
components
Many motherboards include onboard devices (such as network cards, audio
cards, video cards, or USB and Firewire connections).
Faceplate
connectors
A faceplate fits over the motherboard's ports to secure them and protect the
motherboard from dust and debris.
Motherboard
Component
Features
BIOS chip
The BIOS chip is firmware (hardware hard-coded with software) attached to
the motherboard and is essential in booting the computer.
The CMOS battery supplies power to the CMOS to retain system settings used
CMOS battery by the BIOS during system boot.
Chipset
The chipset is a group of chips that facilitate communication between
the processor, memory components, and peripheral devices. The
chipset controls the bus speed and also power management features
Jumpers
Jumpers are electrical connection points that can be set to control
devices and functions attached to the motherboard. Many functions
previously performed by jumpers can now be configured in the CMOS
or are configured automatically.
Expansion Buses
Slot
Characteristics
PCI
Peripheral Component Interconnect supports a 32- or 64-bit I/O bus providing
compatibility with both 486 and Pentium. PCI slots are typically white.
PCIe
Peripheral Component Interconnect Express PCI Express (PCIe) is a next
generation I/O bus architecture. Rather than a shared bus, each PCIe slot links to
a switch which prioritizes and routes data through a point-to-point dedicated
connection and provides a serial full-duplex method of transmission. PCIe slots
are typically white.
AGP
Accelerated Graphics Port AGP is similar to PCI, but designed specifically for
graphics support. Motherboards that provide AGP support have a single AGP
slot. AGP is commonly used for video cards in modern computer systems, but is
being replaced by PCIe. AGP slots are typically brown.
Processors
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Both Intel and AMD processors work in PC systems and support Windows software.
A 32-bit processor can process 32-bits of information at a time; a 64-bit processor can
process 64-bits of information. The biggest advantage of 64-bit processors over 32-bit
processors is in the amount of memory they can use. 32-bit processors have a limit of 4GB.
Processors operate using an internal clock that is the same as, or is a multiple of, the
motherboard bus speed. The speed is represented in MHz and is also referred to as
the frequency.
A multiple core processor has multiple processors within a single processor package.
Cache is memory that the processor can access directly without using the system RAM. There
are three types of processor cache: L1, L2 and L3.
Hyper-threading is a feature of some Intel processors that allows a single processor to run
threads in parallel, Hyper-threading enables a processor to execute two threads at the same
time.
Throttling is the process of modifying the operating characteristics of a processor based on
current conditions.
Virtualization allows a single physical machine (known as the host operating system) to run
multiple virtual machines (known as the guestoperating systems)
RAM
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Random Access Memory (RAM) can be classified as one of two types: Dynamic or
Static
SDRAM is synchronized with the system bus clock, allowing it to receive
instructions in a continuous flow.
DDR accepts a single command and two consecutive data sets per bus clock cycle.
DDR2 doubles the data transfer rate of DDR, for four times the bandwidth of
SDRAM.
DDR3 doubles the data transfer rate of DDR2, for eight times the bandwidth of
SDRAM (twice that of DDR2).
Dual-channel systems use two memory controllers, while triple channel systems
use three memory controllers. Each memory controller can communicate with one
or more memory modules at the same time.
DDR3 can all work in dual-channel systems (depending on the memory supported
by the motherboard); a triple channel system can only use DDR3
BIOS and CMOS
Component
Basic Input
Output System
(BIOS)
Complementary
Metal-Oxide
Semiconductor
(CMOS)
Description
The BIOS is a program stored in a read-only memory (ROM) chip
that the CPU automatically loads and executes when it receives
power.
• The BIOS program controls the startup process and loads the operating system into
memory.
CMOS memory is a special RAM chip powered and maintained by a
small battery that holds basic configuration data your computer
needs in order to start.
• The CMOS battery can be a low-voltage dry cell, lithium mounted on the motherboard.
• The electric current is about 1 millionth of an amp and can provide effective power for
years.
• If the voltage of the battery drops significantly, you may lose your CMOS settings every
time you power-off or power-on your computer. If a CMOS battery fails, replace it and
afterwards reenter the CMOS information.
CMOS
Common reasons for editing the CMOS settings are:
• To change the boot device order.
• To enable or disable motherboard devices.
• To add a password to the setup program to prevent unauthorized access. Note: If
you set a BIOS password and then forget it, you will be unable to edit CMOS
settings. To remove the password for most motherboards, move or remove a
jumper, then replace it after a specific period of time. Removing the battery also
works, but will remove all CMOS data, not just the BIOS password.
• To configure processor or memory settings (such as when you need to set
operating speeds or when you want to overclock hardware settings).
• (In rare cases) To manually configure device properties for legacy devices.
Video
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Video cards must be compatible with the buses or slots on the motherboard.
Common slot types used by video cards are typically AGP and PCI express.
Video cards include a processor (called a graphics processing unit or GPU) that
takes over video rendering from the CPU, thereby increasing video performance.
Video cards have built-in memory. The amount of memory on the card effects
performance as well as other characteristics of the display.
The quality of images and animations are determined by the following
characteristics of display. The capability of your display depends on both the video
card and the monitor support.
Many videos cards include an HDMI connector for connecting to an HD TV or
monitor with an HDMI port.
By purchasing a video card with dual heads (two output connectors capable of
displaying video simultaneously), you can use dual monitors (as long as the
operating system supports dual monitors).
Some video cards include features that allow them to receive video signals and
output them to a TV source.
– Analog: S-video, Digital: HDMI, or DVI
A VGA (analog) monitor connects using a DB-15 connector.
A LCD (digital) Monitor usually connects to an DVI connector.